# -*- coding: utf-8 -*-
"""
Created on Thu Apr 25 12:42:45 2019

@author: yaoyu
"""

ls = [[1,1],[2,3],[4,5]]
fname = 'text.txt'
f = open(fname, 'w')
for item in ls:
    f.write(','.join([str(i) for i in item]) + '\n')
f.close()